In numbers

As Jessica Panetta describes her daily battle with chronic pain, she pauses, and then takes a few short breaths. She apologises, explaining that sometimes it hurts to breathe.

Ms Panetta, 32 from Melbourne, is one of the estimated 700,000 Australian women with endometriosis, a little understood disease in which tissue, similar to what normally lines the uterus, grows in other parts of the body, causing pain.

In her case, it's taken root in her chest cavity and engulfed her diaphragm, not only making it hard for her to breathe, but on her worst days, laugh, sneeze and cry.

"During a flare up, it's like barbed wires are being pulled through my ribs," said Ms Panetta, who wants to work but has been deemed to have total permanent disability. "On a good day, I'm still taking painkillers every four hours."

With endometriosis, there is no correlation between severity of disease, which is divided into four stages, and intensity of pain.

Sarah Holdsworth-Carson is an endometriosis researcher at the Royal Women’s Hospital in Melbourne.

The researchers, from the University of Melbourne and the Royal Women’s Hospital in Melbourne, said the results highlighted the "complex interaction" between the disease, BMI and pain.

"We have shown that BMI is linked to endometriosis, and for the first time, we demonstrate that obesity is associated with an increase in disease severity and a reduced frequency of stage I endometriosis," the authors said.

"It remains unclear what role BMI has in the cause or effect of the disease, although there is evidence to support a genetic interaction."

It's been suggested that only "skinny" women get endometriosis, but the study shows the average sufferer has a BMI in the upper healthy range, not "skinny" or underweight.

The study also corroborates the link between endometriosis and metabolism, as earlier research has shown that sufferers are more likely to have high cholesterol.

"The finding [that women who are obese are more likely to have severe disease] is unexpected to a degree because normally women who are obese have higher oestrogen levels, which is usually something that comes across with women who have endometriosis," lead researcher Sarah Holdsworth-Carson said.

"We’re unsure what this means, whether it shows the disease progresses more quickly in obese women, or whether they show fewer symptoms in the earlier stages of the disease and therefore not seeking treatment."

The study involved 509 women of reproductive age who reported pelvic pain and underwent laparoscopic surgery at the Royal Women’s Hospital. Of those, 357 had surgically confirmed endometriosis.

The results are some of the first to come from a larger study investigating the genetic drivers of the "tricky" disease with the aim of finding targets for new treatments and better diagnosis.

Dr Holdsworth-Carson said researchers were at the early stages of understanding the disease and desperate for more funding.

"We need simple measures that doctors can use ... by calculating their BMI, it’s a simplistic way of providing the phenotype of a patient. There is a need for patient stratification," she said.

Professor Jason Abbott from UNSW.Credit:Endometriosis Australia

"The current staging system is based on what the surgeon sees during surgery and has no correlation with pain symptoms, so that's one of the inadequacies."

A clinical application, she said, was that surgeons needed to be aware of the need to provide more time for surgery in obese women as they were more likely to have extensive endometriosis requiring removal.

Professor Jason Abbott, medical director at Endometriosis Australia, said it was too early to say what the findings meant for women with endometriosis, dubbed a "silent epidemic".

"We do know that the cause of endometriosis is about 50 per cent related to your genetics and genes are also important in obesity," he said.

"It may be that the gene that 'turns on' endometriosis has a 'turn off' effect on weight gain. Clearly the more we know around the causes and these links, we may have better answers to a whole variety of diseases and better treatment options for endometriosis."

Loading

He encouraged all women to look after their health and weight.

"It is imperative that a general healthy weight range be maintained for the benefits that go well beyond reproductive health and endometriosis. Being in a healthy weight range improves fertility and an exercise program is good for heart, bone and mental health," he said.

"Women with endometriosis who have pain or fertility issues will always benefit from being in a healthy weight range and having good exercise habits."

Ms Panetta, who is a healthy weight and led an active lifestyle before the pain became too extreme, said the findings gave her a "glimmer of hope".

Despite feeling pain since she was 13, she was only diagnosed with endometriosis at 22. She has endured eight surgeries but is still in "agonising" pain.

"I’ve met so many women with so many different cases of endo and they come from so many backgrounds and are all different shapes and sizes, so it’s hard to say what this study means to me," she said.

"On behalf of myself and my endo sisters, we're incredibly thankful for all the researchers trying to help us, because even if it's not a cure, they're trying to find something that can help us manage the pain."

The study - the world’s largest to compare BMI with endometriosis that has been surgically diagnosed - has been published in the latest Journal of Endometriosis and Pelvic Pain Disorders.